Controls on earthquake rupture and triggering mechanisms in subduction zones
Citable URI
https://hdl.handle.net/1912/3586Location
Salton TroughHokkaido Corner
DOI
10.1575/1912/3586Keyword
Earthquake prediction; Earthquake zonesAbstract
Large earthquake rupture and triggering mechanisms that drive seismicity in
subduction zones are investigated in this thesis using a combination of earthquake
observations, statistical and physical modeling. A comparison of the rupture
characteristics of M ≥ 7.5 earthquakes with fore-arc geological structure suggests that
long-lived frictional heterogeneities (asperities) are primary controls on the rupture extent
of large earthquakes. To determine when and where stress is accumulating on the
megathrust that could cause one of these asperities to rupture, this thesis develops a new
method to invert earthquake catalogs to detect space-time variations in stressing rate.
This algorithm is based on observations that strain transients due to aseismic processes
such as fluid flow, slow slip, and afterslip trigger seismicity, often in the form of
earthquake swarms. These swarms are modeled with two common approaches for
investigating time-dependent driving mechanisms in earthquake catalogs: the stochastic
Epidemic Type Aftershock Sequence model [Ogata, 1988] and the physically-based rate-state
friction model [Dieterich, 1994]. These approaches are combined into a single
model that accounts for both aftershock activity and variations in background seismicity
rate due to aseismic processes, which is then implemented in a data assimilation
algorithm to invert catalogs for space-time variations in stressing rate. The technique is
evaluated with a synthetic test and applied to catalogs from the Salton Trough in southern
California and the Hokkaido corner in northeastern Japan. The results demonstrate that
the algorithm can successfully identify aseismic transients in a multi-decade earthquake
catalog, and may also ultimately be useful for mapping spatial variations in frictional
conditions on the plate interface.
Description
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2010
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Suggested Citation
Thesis: Llenos, Andrea L., "Controls on earthquake rupture and triggering mechanisms in subduction zones", 2010-06, DOI:10.1575/1912/3586, https://hdl.handle.net/1912/3586Related items
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